1. Field of Technology
The present invention relates generally to a receipt printer or other type of printer used in a POS system, and relates more particularly to a printer in which a remaining paper detector is removably installed for detecting how much paper remains on a paper roll in the roll paper compartment.
2. Description of Related Art
Paper rolls made by winding a recording paper tape as a recording medium onto a core are commonly used in receipt printers. A paper roll is then housed in a roll paper compartment, the paper is pulled from the roll and printed using a thermal print head, for example, and the printed paper is then cut to a suitable length by a paper cutter for issuance as a receipt. To make replacing the roll paper easier, some printers of this type have the paper roll set directly on the bottom of the roll paper compartment and pull the paper tape from the compartment with the paper roll rotating directly against the compartment bottom rather than passing a spindle through the core of the roll and rotatably supporting the roll on this spindle.
So that different widths of roll paper can be used in printers using this type of roll paper compartment, Japanese Unexamined Patent Appl. Pub. 2002-3022 teaches a printer in which one side of the roll paper compartment is a movable divider. This divider can be moved widthwise to the printer and set to the width of roll paper loaded in the roll paper compartment.
Printers that have a remaining paper detector in the roll paper compartment for detecting when the amount of paper left on the roll declines to a specific threshold level are also known. One such remaining paper detector has a detector element that enters the hollow core of the paper roll when the amount of paper left on the roll drops to a predefined level. When this detector element enters the hollow core, a switch operates to output a signal indicating that there is only a little paper left. See, for example, Japanese Unexamined Patent Appl. Pubs. 2002-3022 and H09-295436.
Obviously not all receipt printers, for example, have a remaining paper detector pre-installed in the roll paper compartment, and there are therefore cases in which a remaining paper detector (also called a near-end detector) is later added.
If the remaining paper detector operates by means of a detector element that enters the hollow core of the paper roll, it may also be necessary to adjust the height and orientation of the detector element according to the attitude of the printer, for example, so that the detector operates correctly.